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cache-nodb/nodb.go

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// Copyright 2014 lunny
// Copyright 2014 The Macaron Authors
//
// Licensed under the Apache License, Version 2.0 (the "License"): you may
// not use this file except in compliance with the License. You may obtain
// a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
// License for the specific language governing permissions and limitations
// under the License.
package cache
import (
"errors"
"fmt"
"os"
"github.com/Unknwon/com"
"github.com/lunny/nodb"
"github.com/lunny/nodb/config"
"github.com/tango-contrib/cache"
)
var (
ErrDBExists = errors.New("database already exists")
)
// NodbCacher represents a nodb cache adapter implementation.
type NodbCacher struct {
dbs *nodb.Nodb
db *nodb.DB
filepath string
}
// Put puts value into cache with key and expire time.
// If expired is 0, it lives forever.
func (c *NodbCacher) Put(key string, val interface{}, expire int64) (err error) {
var v []byte
switch val.(type) {
case []byte:
v = val.([]byte)
default:
v = []byte(com.ToStr(val))
}
if err = c.db.Set([]byte(key), v); err != nil {
return err
}
if expire > 0 {
_, err = c.db.Expire([]byte(key), expire)
return err
}
return nil
}
// Get gets cached value by given key.
func (c *NodbCacher) Get(key string) interface{} {
val, err := c.db.Get([]byte(key))
if err != nil {
return nil
}
if len(val) > 0 {
return string(val)
}
return nil
}
// Delete deletes cached value by given key.
func (c *NodbCacher) Delete(key string) error {
_, err := c.db.Del([]byte(key))
return err
}
// Incr increases cached int-type value by given key as a counter.
func (c *NodbCacher) Incr(key string) error {
if !c.IsExist(key) {
return fmt.Errorf("key '%s' not exist", key)
}
_, err := c.db.Incr([]byte(key))
return err
}
// Decr decreases cached int-type value by given key as a counter.
func (c *NodbCacher) Decr(key string) error {
if !c.IsExist(key) {
return fmt.Errorf("key '%s' not exist", key)
}
_, err := c.db.Decr([]byte(key))
return err
}
// IsExist returns true if cached value exists.
func (c *NodbCacher) IsExist(key string) bool {
num, err := c.db.Exists([]byte(key))
return err == nil && num > 0
}
func (c *NodbCacher) new() (err error) {
if c.db != nil {
return ErrDBExists
}
cfg := new(config.Config)
cfg.DataDir = c.filepath
c.dbs, err = nodb.Open(cfg)
if err != nil {
return fmt.Errorf("cache/nodb: error opening db: %v", err)
}
c.db, err = c.dbs.Select(0)
return err
}
// Flush deletes all cached data.
func (c *NodbCacher) Flush() (err error) {
if err = os.RemoveAll(c.filepath); err != nil {
return err
}
c.dbs.Close()
c.db = nil
c.dbs = nil
return c.new()
}
// StartAndGC starts GC routine based on config string settings.
func (c *NodbCacher) StartAndGC(opt cache.Options) error {
c.filepath = opt.AdapterConfig
return c.new()
}
func init() {
cache.Register("nodb", &NodbCacher{})
}